Mount Backblaze B2 as a Drive on Windows, Mac or Linux

Backblaze gives you an API, not a File Explorer window

Checked 24 September 2026 against Backblaze's own documentation. B2 is a good place to park archives, build artifacts and media because the price is easy to reason about: "First 10GB storage is always free", storage from $6.95 per TB per month, and a "Free 3x monthly egress" allowance with overage at $0.01 per GB.

What Backblaze publishes for the desktop is integration documentation — how to point s3cmd, the AWS SDKs, rclone and third-party clients at the S3-compatible API. There is no first-party file manager that drops a bucket into File Explorer or Finder, so you build that yourself. If you want a window with a transfer queue instead of a drive letter, the Backblaze B2 client page covers that and this one will not repeat it.

What every method needs: an endpoint, a key and a bucket

The endpoint. B2's S3-compatible API lives at https://s3.<region>.backblazeb2.com, where the region looks like us-west-004. Backblaze shows the exact value on the bucket as its Endpoint URL, and its s3cmd guide gives the rule: "if your endpoint URL is s3.us-west-004.backblazeb2.com, enter us-west-004."

https://s3.us-west-004.backblazeb2.com
        ^^^^^^^^^^^ region, copied from the bucket's Endpoint URL

The key. Create an application key under App Keys. B2 maps its two values onto the S3 names directly: keyID is the aws_access_key_id and applicationKey is the aws_secret_access_key. Your master application key "is shown only when you generate it, and it is not shown again", and it is the wrong key here anyway. A standard key can be restricted to one bucket and narrowed with namePrefix, which "limits access to file names that begin with a specific prefix"; the access type is Read and Write, Read Only or Write Only.

The bucket. B2 buckets are allPrivate, which "require an authorization token for every download", or allPublic, which "allow any user to download the files in the bucket". Private is right for a mount, since every method below authenticates. For S3-API use, keep to the stricter S3 naming rules: 3 to 63 characters, lowercase.

The four ways, side by side

One row deserves a warning before you buy. CloudMounter's macOS build lists Backblaze among its services; the Windows build drops pCloud, Backblaze and OpenStack. If you are on Windows and Backblaze is why you are shopping, CloudMounter is not the answer. And Cyberduck, the usual free recommendation, does speak Backblaze B2 on macOS and Windows but does not mount at all — that is deliberately Mountain Duck's job.

Method 1: AnyStorage, with no filesystem driver

AnyStorage 0.2.25 shipped on 23 September 2026 for macOS 11 or newer, Windows 10 or newer and Linux, with brew install --cask kilerd/tap/anystorage on macOS. Backblaze B2 is one of its 20-plus connection types rather than an S3 endpoint you assemble by hand: paste the endpoint, the keyID and the applicationKey and the bucket opens as a folder tree with tabs, search and a transfer queue.

The mount is a second step and installs nothing in the kernel. Open Services in the sidebar, switch to the WebDAV tab and press Start. The server listens on http://127.0.0.1:3211 with HTTP Basic auth always on — username anystorage, a 24-character password generated on first use. Map it with the tool the OS already has: Map network drive on Windows, Cmd+K on macOS, dav://127.0.0.1:3211 on Linux. Every connection open in the app appears as a folder at the WebDAV root, so a B2 bucket sits next to an S3 bucket under one drive letter — the wider picture is on the S3 GUI client page.

What it costs you. The free tier allows two connections and serves the mount read-only, so a writable drive letter is a Pro feature. There is no TLS on the local server, which is why it binds to loopback, and no file locking or offline cache. Windows adds its own WebDAV client quirks — a deprecated WebClient service, a BasicAuthLevel registry value that refuses Basic auth over plain HTTP, and a 50,000,000-byte transfer cap — worked through in mount cloud storage as a local drive.

Method 2: rclone mount, the free universal route

rclone has a native b2 backend as well as its generic s3 one. The native backend takes account, documented as "Account ID or Application Key ID", and key. The documentation is blunt about which to use: "you must put the *applicationKeyId* as the account — you can't use the master Account ID. If you try then B2 will return 401 errors."

On Windows, "to run rclone mount on Windows, you will need to download and install WinFsp" — a kernel-mode driver covering "Windows 7 to Windows 11 and the x86, x64 and ARM64 architectures". On macOS the mount needs macFUSE or FUSE-T, or the separate rclone nfsmount command.

rclone config create b2remote b2 account KEY_ID key APPLICATION_KEY
rclone mount b2remote:my-bucket X: --vfs-cache-mode writes --network-mode

Pick a cache mode deliberately: rclone warns that many applications will not work with files on a mount "without --vfs-cache-mode writes or --vfs-cache-mode full", because in the default off mode a file cannot be opened for both read and write. --network-mode presents the result as a network drive rather than a fixed disk. One B2-specific behaviour: "the default setting of B2 is to keep old versions of files", so every overwrite creates a version, and --b2-hard-delete turns deletes into real deletions. If the mount will not start, see rclone mount FUSE errors.

Method 3: Mountain Duck, the only one with an offline cache

If your requirement is "open yesterday's file on a plane", this is the only answer here. Mountain Duck lists Backblaze B2 among its protocols and, since version 5, installs no filesystem driver: "the new Integrated connect mode syncing with File Provider (macOS) and Cloud Files (Windows) APIs. No device driver installation or network mount required." Version 5.3.2.29785 is dated 25 August 2026 and needs macOS 13 or later or Windows 10 or later. The catch is the price: per seat, tied to one major version, and the store quotes nothing until you pick a user count and a currency. No Linux build. See Mountain Duck alternatives.

What B2's S3 API does not do

Most S3 tooling works unchanged, which is the point. The gaps are documented, and they are where a client occasionally surprises you.

How a mount spends your egress allowance

A mount reads on demand, so every directory listing, every thumbnail and every preview becomes a real request to B2. Backblaze's pricing gives you a "Free 3x monthly egress" allowance — three times your average stored data, free — then $0.01 per GB.

Three usage patterns cost very differently. Fetching the occasional file costs almost nothing, and is what a mount is for. Letting a backup tool or a search indexer walk the whole mount nightly turns a few megabytes of reading into a full read of the bucket, and quietly exhausts the allowance. Scrubbing a large video is in between: range requests mean the whole file is not downloaded, but repeated seeks are still traffic.

The practical habit: keep the mount for interactive work, move bulk data with the app's transfer queue or rclone copy, and scope that key read-only.

When it fails, and what the failure means

1. Wrong region in the endpoint. https://s3.us-west-001.backblazeb2.com for a bucket in us-west-004 is not a bucket that exists as far as your client is concerned, and S3 clients usually report that as a credentials or signature problem rather than a routing one.
2. `InvalidAccessKeyId` from an S3 client. Backblaze's S3-compatible reference does not document its authentication error codes, so treat the string as your client saying the access key was not recognised, and check that you pasted keyID and not the account ID. rclone's native backend documents the same trap: use the applicationKeyId as the account, or "B2 will return 401 errors."
3. A key that is too narrow. A bucket-restricted key without listing capability fails at the first directory listing, which is the first thing any mount does. Backblaze's s3cmd guide names the symptom: "If you encounter a 403 error during verification, ensure your application key has the 'List All Bucket Names' permission enabled."
4. A `namePrefix` you forgot. A key scoped to builds/ mounts happily and then shows an empty folder everywhere else — a working restriction that looks like a broken mount.

Questions